Face down/belly down armbar

I don't know the "proper" name of the technique, but I have heard it called both a face down and belly down armbar. This is when you get stacked while you have already secured an armbar from the guard and you roll with the pressure, putting you and your opponent face down with their arm still trapped.

A week ago we were drilling armbars from the guard and what to do when stacked or if they try to pull away. While being stacked and rolling them, we were taught to remove the leg hooking the head, then push down on the side of the head with your shin while rolling, and finish it on the ground with your shin pinning their head to the ground.

I can't remember where, but recently I saw a MMA match (possibly pride) where someone locked on the armbar from the guard and got stacked, rolled with it and finished face down. They kept their leg hooked around their opponents head the whole time though.

I know there are lots of different variations on just about every move there is. Are there any advantages to keeping their head hooked with your leg opposed to driving it into their head? In terms of disadvantages, I hurt my toe pretty badly when I forgot remove the leg hooking the head, although if more careful I'm sure that can be easily avoided.

the fedor vs coleman armbar is my fave armbar and my specialty.
I love that sucker.
The perfect example is when fedor did it, just watch it over and over and over.
I love to do it all the time from gaurd. The moment i can snatch a hand i bring it close to my body and pivot and jerk my hips out hard.
Nearly every wrestler I'v rolled with, this is how I got em.
Just remember, you have got to pivot right and then grab the arm right, for me after that it all comes naturally,.

Yup, thats what I was thinking, so unless I am missing something in that description this might not be the bes idea.

You turn over with your legs still hooked over the head, and it is important to keep them there and pull in with your feet, like you're trying to squish him on the inside of your knee, otherwise he'll just pull out and pass guard.

The only reason you're switching your leg is to give you leverage to pull the arm out (extend it) so you can lock it. It has nothing to do with pinning his head to the ground.

You will most typically use the shin against the side of the head when attempting an armbar from rear mount (slipping into the juji roll), not when rolling through while being stacked.

I've never switched the leg like that when rolling through while being stacked. Normally at that point you should have his arm extended enough to where you shouldn't need the leverage of the shin against the head. Otherwise, you went for it too soon. I agree with everyone else that you're creating an opportunity for escape.

The shin on their head can serve to flatten your opponent out and extend their arm. This can really be helpful on a big guy. And a face down armbar is probably the easiest way to get an armbar on a big dude. The only way I have been shown to do this involves using the gi, so I don't know about no gi.

I've been taught otherwise, but it wasn't for the exact situation mentioned. What I've been taught is that standard and shin/head armbars are both good grappling, just useful in different situations (Lawdog mentioned one of them).

Another example of someone doing the shin to the side of the head in MMA is Arlovski vs. Aaron Brink.